Key Value System

From OpenStreetMap

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OSM features a simple yet powerfull system for assigning properties to objects. Every Data Primitive can have pairs of keys and values associated with it. It is free to the users to find an ontology to give special keys a meaning. Clients can implement different behaviour, if objects have specific keys associated.

As example, if a street has the key "speedlimit" set to "10mph", a client could use this information in calculating faster routes by using other streets.

Might be a good idea to check the Map Features for what kind of keys/values you should use.

What's done now

Almost any editor currently available support any arbitrary keys/values. As example, in the applet key/value can be entered either in a template form (for some specific keys as "name") or as a table of any arbitrary key/value.

This stuff has to be written (but it isn't super hard): You can call something a motorway, someone else can call it an autobahn or a freeway and the software knows they are basically the same thing. A feature like a subway station will know how to draw itself and with what logo. Example where key and value look like 'key/value' are: oneway=1 (where 1 == true == True == TRUE == yes..., 0 == false == FALSE...). Another example would define the class of a street segment: class=motorway. The motorway class would have metadata of key/value pairs such as implies/allowsCars=true, where allowsCars is another key. Others might look like displayStyleLineColour=blue or displayLogo=http://someimage.jpg.